Circuit controlling device



y 3, 1945. c. F. ROBBINS 2,375,387

CIRCUIT CONTROLLING DEVICE Filed Oct. 31, 1941 5 Sheets-Sheet l II ll 2,Z

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CIRCUIT CONTROLLING DEVICE Filed Oct. 31, 1941 5 Sheets-Sheet 2Fnirimlllllll y 1945. c. F. FQOBBINQ CIRCUIT CONTROLLING DEVICE 3Shets-Sheet 3 Filed Oct. 31 1941 Patented May 8, 1945 CIRCUITCONTROLLING DEVICE Clyde F.-Robbins, Milwaukee, Wis assignor toCutler-Hammer, Inc., Milwaukee, Wis., a corn tation of DelawareApplication October 31, 1941, Serial No. armor (cl. zoo-31.5)

13 Claims.

This invention relates to circuit controlling devices, and moreparticularly to automatic temperature control switches for use inconnection with electric refrigerators.

The invention has among its objects to simplify the construction,increase the life and improve the operating characteristics of switchesof the aforementioned type.

Another object is to provide a refrigerator control switch which is ofrelatively small size'and is built up largely of stamped and formedsheet metal parts which can be readily manufactured and assembled at lowcost.

Another object is to provide a refrigerator control switch having animproved snap operating mechanism which is simple in construction andexceedingly positive and reliable in operation.

Another object is to provide a control switch for electric refrigeratorshaving an improved manual adjusting mechanism for regulating thetemperature which is maintained within the refrigerator cabinet, and foralso rendering the refrigerator inoperative for defrosting.

Another object is to provide a refrigerator control switch in which theswitch contacts and their associated terminal members constitute a unitwhich is detachably secured to an assembly inscope of the appendedclaims.

In the drawings,

Figure 1 is a top elevational view of a control switch embodying theinvention, a, cover and a front plate for the switch being shown insection;

Fig. 2 is a sectional view taken on line 2-4 of Fig. 1;

Fig. 3 is a sectional view taken on line 3-3 of Fig- 2;

Fig. 4 is a sectional view on line 4-4 of Fig. 1 illustrating the switchoperating mechanism ll circuit closing position;

Fig. 5 is a fragmentary sectional view alsc taken on line 4-4 of Fig. 1illustrating the switch operatin mechanism in circuit opening position;

Fig. 6 is a sectional view on line 6-6 of Fig. 1;

Fig. 7 is an exploded perspective view of certain of the parts shown inFigs. 1 and 2, and

Figs. 8 and 9 are diagrammatic views illustrat- 4 in circuit closing andcircuit opening positions.

The refrigerator control device illustrated'in the drawings includes aswitch unit I and a unitary operating assembly therefor including a snapoperating mechanism 2 and a pressure responsive device 3. The snapoperating mechanism 2 and pressure responsive device 3 are mounted upona. rectangular base plate 4 having a U- shaped cover 5 mounted thereon,and said pressure responsive device has a loading spring 6 associatedtherewith which is adjustable by a knob l. I

More specifically switch unit I as shown in Figs. 3 and 4 is providedwith a molded insulating base 8 which carries a pair of stationarycontacts 8-9 and a cooperating bridging contact l0. Insulating base 8 issecured to a downwardly extending projection H on the rear end of baseplate 4 by a screw I! (Fig. 2) and said insulating base is shaped to fitwithin the rear end of cover 5. Stationary contacts 9 and bridgingcontact I 0 are located within a recess formed in the front face ofinsulating base 8 and said stationary contacts are carried by a pair ofterminal members II which are held in position upon said base by rivetsI4. The rear face of insulating base I is provided with a circularrecess I5 for receiving a conventional attachment plug and the terminalmembers I3 are provided with prongs it which extend rearwardly throughopenings in said base into said recess for engagement with the contactsassociated with the attachment plug. As shown in Fig. 3, bridgingcontact I0 is biased to engage its associated stationary contacts 9 by aspring H which is held under compression between said bridging contactand an insulating cover plate l8 secured to the front end of base ill bya screw I9 shown in Fig. 2. Bridging contact, I0 is movable out ofengagement with its associated stationary contacts 9 against the actionof spring H by a pair of insulating bell crank levers v2i! which arelocated adjacent the opposite ends of said bridging contact as shown inFig. 3. As shown in Fig. 4, each of the bell crank levers 20 isfulcrumed upon a ledge 2| formed on the front face of insulating base 8and each has an upstanding arm 22 which is located to the rear ofbridging contact l0 and a forwardly extending arm 23.

The snap operating mechanism 2 for switch unit i is mounted upon a pairof upstanding projections 24 formed on the opposite sides of an opening24' in base plate 4, and said mechanism comprises an operating lever 25,a control lever 26 and apair or over-center springs 21. As shown in Fig.7, operating lever 25 comprises a rectangular .shet metal stampinghaving an aperture forming side arms 28-28 and end cross bars 29 and 30,and control lever 26 also comprises a sheet metal stamping having anaperture forming side arms 3l3l and end cross bars 32 and 33. Also asshown in Fig. 7, the upstanding projections 24 on base plate 4 are eachformed to provide a pair of oppositely disposed V-shapecl bearingnotches 34 and 35 and the side arms 28 of operating lever 25 areprovided with ear rojections to for engaging within the bearing notches36 while the side arms 3| of control lever 25 are provided with earprojections 31 for engaging within the bearing notches 35; The earprojections lit and ill of levers 25 and 26 are yieldingly held withintheir respective bearing notches 34 and 35 by the over-center springs2'8 and as shown in Figs. 3 and 4 the rear ends of said springs areattached adjacent opposite ends of the cross bar (it of operating lever25 and the front ends of said springs are attached adjacent oppositeends of the cross bar (52 of control lever it. For a purpose hereinafterset forth the bearing notches 343 for operating lever 25 are spacedupwardly with respect to the bearing notches 35 for control lever in. Asshown in Fig. 2, the cross bar to or operating lever 25 is located abovethe forwardly extending arms 23 on cell crank levers 2t and upwardmovement of the rear end of said operating lever is limited byengagement of said cross bar with an adjustable screw stop 39 which isthreaded into a projection 4t formed on the front end of insulating base23. The cross bar 32 or control lever is spaced forwardly with respectto the cross bar 2d of operating lever 26 and upward movement or" thefront end of said control lever is limited by stop projections ll formedon the side arms 2d of base plate 6.

The operation oi the aioredescribed snap operating mechanism will bereadily understood by reference to 8 and 9. As shown in Figs. i and 8,the of springs ll are normally located above the hearing notches 3d andwhereby operating lever 25% is normally held in engagement with itsassociated screw stop 39 and control lever is normally held inengagement with the stop projections ll on base plate Q. When iront endof control lever 26 is swun downwardly away from the stop projections iithe axes of sprin ii are moved downwardly across the bearing notches 3 3and lever 25 is thus moved with a snap action away from the screw stop39 and into engagement with the "forwardly extending arms 23 of hellcranks lid to move bridging contactill out of engagement with. itscooperating stationary contacts against the action of spring ll, asshown in Fig. 9. Downward movement of the front end of operating leveris limited by engagement of the cross bar with the upper face of baseplate I} and upon downward movement of said control lever into saidlimit the axes of springs ll are still located above the bearing notches35. The over-center springs ll thus act to constanly bias the front endof control lever 26 upwardly and upon release of said lever the samereturns under the action of said springs to the position shown in Fig.8. Upon return ed lever 26 to the position shown in Fig. 8 the axes ofsprings Eli are moved upwardly across the bearing notches 3 to efiectsnap return movement of operating lever into the position shown in Fig.8 to permit return of bridging contact In to circuit closing positionunder the action of springs H.

The bridging contact ID of switch unit I is operated by the pressureresponsive device 3 through the medium of the snap operating mechanism2. As shown in Fig. 2, the pressure responsive device 3 includes aflexible metal diaphragm N which is sealed within the opening in a rigidcup member 45 havin a closed tube extension 36 connected thereto.Diaphragm 44 is spaced with respect to the bottom wall of cup member 65to provide a sealed chamber 41 and said chamber and the tube 36 arefilled with a thermal responsive fluid such as methyl chloride. The openend of cup member t5 is provided with an outwardly extending flange ofrectangular form and said cup member is secured to the under side ofbase plate 4 by screws 48 (Fig. 4) which are located at the corners ofsaid flange.

The loading spring ii associated with the pressure responsive device 3is of coil form and extends upwardly from diaphragm 46 through theopening in base plate 4 and through the apertures in levers Eli and 2s.The lower end of loading spring 6 has a circular cup washer 49associated therewith which bears against the upper face of diaphragm id,and is operatively connected to control lever 28 of the snap operatingmechanism through the medium of a stirrup lit. Cup washer is is formedof sheet metal and is provided with an outwardly extending peripheralflange 5i and an upwardly extending center projection 52 which engageswithin the opening in loading sprin 6. Stirrup 5b is also formed ofsheet metal and comprises a ring-shaped yolre 53 having upstanding armsml formed on opposite sides thereof and an inwardly extending circularflange o5 formed on the under side thereof. Flange aid is provided withdiametrically disposed humps 56 which engage the under side or" theflange hi on cup member 39 and the arms 5d are disposed at right anglesto said humps and are provided with slots ol for receiving inwardlyextending bearing projections 58 formed on the side arms 36 or controllever it. The upper ends of slots 51] are shaped to provide li shapedsurfaces for engaging the top faces of bearing projections SB, and asbest shown in Fig. 3 said bearing projections are located in front ofthe bearing projections Bl whereby the control lever 26 is movable bythe stirrup from the position shown in Fig. 4 to the position shown inFig. 5 under the action oi loading spring 6.

Assuming that the switch is employed to control energization of anelectric refrigerator, the tube lli may be secured to the evaporator ofthe refrigerator and the pressure of the fluid in chamber ll of pressureresponsive device 3 will then vary in accordance with changes in thetemperature of the evaporator. Thus upon warming of the evaporator thepressure oi the fluid in chamber ll will increase to eiiect expansion ofdiaphragm do against the action of loading spring During expansivemovement of diaphragm M stirrup 50 is maintained in engagement withwasher til under the action of springs ill and at predetermined hightemperature determined by the opposing force of loading spring iicontrol lever 2c is moved upwardly into circuit closing position toeffect starting of the refrigerator. Upon starting of the refrigeratorthe pressure of the fluid in chamber ll will decrease due to cooling ofthe evaporator, and diaphragm 3d contracts under the action of loadingspring 8. Upon contraction of diaphragm it th stirrup 50 asvaeav movestherewith and upon a predetermined tem-- perature drop lever 28 is moveddownwardly into its circuit opening position to eifect stopping of therefrigerator. As is apparent, variation of the degree of compression ofspring varies the temperature values at which the refrigerator isstarted and stopped. Also adjustment of screw stop 89 varies theposition of control lever 25 to vary the point at which said lever isoperated during downward movement of control lever 26 from the positionshown in Fig. ti toward the position shown in Fig. 5. Adjustment ofscrew stop 39 therefore varies the differential between the opening andclosing pressures of the switch.

Loading spring 6 is adjustable by the knob l which is rotatablysupported as hereinafter set forth within an opening 60 in a front plate6i. Knob l is provided with a circular hub portion 62 having a camprojection 63 formed on the rear end thereof, and loading spring -6 isadjustable by said cam projection through the medium of a pivoted lever64 and a cam follower B5. Lever 64 is arranged horizontally abovetheloading spring 6 and the same comprises a sheet metal stamping ofgeneral Y-shape including spaced side arms 66 which extend rearwardlywith respect to loading spring 6 and an arm 67 which extends forwardlywith respect to said spring. The rear ends of the arms 68 are providedwith v notches all for receiving downwardly struck bearing projections69 formed on the rear end of the top wall of cover 5 as shown in Fig. 4and the front end of arm 61 is provided witha tip of arcuate form uponwhich cam follower 65 is suspended.

Lever be is operatively connected to loading spring 6 by a nut incarried by a screw ll. Nut 90 engages the upper end of loading spring 6and is shouldered to fit within the same, and screw ll extends upwardlythrough an opening in lever 64 and is provided with a circular flange 52which bears against humps l3 formed on the underside of said lever. Camfollower t5 comprises a sheet metal stamping having an opening "Hi forreceiving the cam projections 53 and a slot 15 on the upper end thereoffor receiving the arcuate tip on the front end of arm Bl of lever 54.The lower end of cam follower 65 is formed to provide an upwardlyextending cam engaging projection l6 and a downwardly extending guidetongue ll which engages within a vertically disposed slot formed byprojections 58 on the front end of base plate 4.

lit will be noted in connection with the foregoing that lever 68 and camfollower 65 are biased upwardly under the action of loading r spring itand the projection M5 on said cam follower is thus held in contact withthe cam projection d3 of knob l. As shown in Fig. 6, cam projection $3is provided with a cam surface 80, and as is apparent said cam surfaceprovides for vertical movement of cum follower 65 and lever 64 betweengiven upper and lower limits upon rotation of knob l in oppositedirections through a given range. Thus when it is desirable to increasethe pressures at which the switch is operated the cam projection 63 isrotated clockwise as viewed in Fig. 6, which moves the cam follower 65downwardly, thereby compressing the loading spring 6 to increase theload on the diaphragm 44. When it is desirable to decrease the pressuresat which the switch operates cam projection '63 is rotatedcounterclockwise by knob l which permits upward movement of cam follower1 55 for a decrease in the loading effect of spring 6.

As is apparent, loading spring 6 is also adjustahie by the screw ii andin practice said screw is shop adjusted with knob 1 set in a givennormal angular position to provide for closure of the switch at apredetermined pressure value. As shown in Fig. 2, the. upper end ofscrew H is provided with a slot and said screw is thus ac-- cessible foradjustment by means of a screw driver which is insertable through anopening 8|- in the top wall of cover 5. As shown in Fig. 2, thedifferential adjusting screw 39 extends. upwardly through an opening inthe top wall of cover 5 and the upper end thereof is provided with aslot to render the same adjustable by means of a screw driver. Screw 39is shop adjusted to provide a predetermined difierential between theopening and closing pressures of the switch and after such adjustment anarm 82'is fixed to the upper end of said screw. Arm 82 cooperates with astop 83 fixed to the upper wall of cover 5 to permit a limited degree ofadjustdifierential.

As hereinbefore stated, knob 7 is rotatably supported within an opening60 in the front plate 8|. As shown in Figs. 3 and 4, plate BI is held inassembled position upon the device by engagement of spaced upwardlyextending projections 85 formed on the lower edge of said plate withinopenings 86 formed in the front end of base plate 4, and by screws 86which extend through openings in the top wall of casing 5 into tappedopenings in projections 87 formed on the upper edge of saidfront plate.As is apparent, knob l is biased upwardly under the action of loadingspring 6 and the hub portion 62 thereof is thus held in engagement withthe upper edge of the opening 80 in plate ti. As shown in Fig. 2, knob lis held in assembled position upon plate ti by engagement of said platewithin a circumferential groove 39 formed in the hub portion 62. Theopening lid in face plate 6| is of such dimensions that knob l may bemoved downwardly into a position wherein groove 89 is disengaged fromplate 65 and said knob may thus be removed or assembled from the frontof the device. As shown in Figs. 1, 2 and 6 the hub portion 62 of knob'i' is provided with a radial projection 90 which cooperates with aninwardly extending stop an upstanding cam projection 93 (Fig. 7) andupon rotation of knob l in a clockwise direction (Fig. 6) into the limitwherein projection 90 on said knob engages the stop projection 9i camprojection 93 is engaged by lug 92 to move switch lever 26 into circuitopening position fordef rosting of the refrigerator. During finalmovement of knob "i into said limit the high point of cam surface 8i? ismoved in a clockwise direction (Fig. 4) beyond the projection 16 on camfollower 65 and said cam follower is then held in its lower limit by acircular cam face 95 on cam projection 63.

What I claim as new and desire to secure by Letters Patent is:

1. In a circuit controlling device, in combination, a housing open atopposite ends and comprising a base plate and a U-shaped cover member, acontrol switch having a contact carrying insulating base mounted withinthe opening in one end of said housing, a pressure responsive devicemounted upon said base plate and having an associated loading springlocated within said housing, said loading spring being of coil form andbeing arranged with its axis substantially perpendicular to said baseplate, a snap operating mechanism for said switch mounted within saidhousing and operable by said pressure responsive device to effectopening and closure of said control switch, a face plate mounted uponsaid housing on the end opposite said contact carrying base and a manualcontrol element rotatably mounted upon said face plate for adjustingsaid loading spring to vary the pressure values at which said controlswitch is opened and closed.

2. In a circuit controlling device, in combination, a housing open atopposite ends and comprising a base plate and a U-shaped cover, acontrol switch having acontact carrying insulating base mounted withinthe opening in one end of said housing, a pressure responsive devicemounted upon said base plate and having an associated loading springlocated within said housing, said loading spring being of coil form andbeing arranged with its axis substantially perpendicular to said baseplate, a snap operating mechanism for said switch mounted within saidhousing and operable by said pressure responsive device to effectopening and closure of said control switch, a face plate mounteduponsaid housing on the end opposite said contact carrying base, and amanual control element mounted upon said face plate and rotatable inopposite directions between given extreme positions to adjust saidloading spring for variation of the pressure values at which saidcontrol switch is opened and closed, said snap operating mechanism beingalso operable by said control member upon movement thereof into oneextreme position to efiect opening of said control switch.

3. In a circuit controlling device, in combination, a housing open atopposite ends and comprising a base plate and a U-shaped cover, acontrol switch having a contact carrying insulating base mounted withinthe opening in one end of said housing, a pressure responsive devicemounted upon said base plate and having an associated loading springlocated within said housing, a snap operating mechanism for said switchmounted within said housing and operable by said pressure responsivedevice to effect opening and closure of said control switch, a faceplate detachably mounted upon said housing on the end opposite saidcontact carrying base and a manual adjusting element detachably mountedupon said face plate and rotatable in opposite directions between givenextreme positions, said control element having a cam associatedtherewith for adjusting said loading spring to vary the pressure valuesat which said control switch is opened and closed and said controlelement also having a projection thereon for operating said snapoperating mechanism to effect opening of said control switch uponmovement of said control element into one of its extreme positions.

d. In a circuit controlling device, in combination, a housing open atopposite ends, a control switch including an insulating contact carryingbase mounted within the opening in one end of said housing, a pressureresponsive device mounted uponone of the walls of said housing andhaving a loading spring associated therewith located within saidhousing, a snap operating mechanism for said switch mounted within saidhousing and operable by said pressure responsive device to eilectopening and closure of said control switch, a face plate detachablymounted upon said housing on the end opposite said base, and means foradjusting said loading spring including a manual control memberrotatably mounted upon said face plate and having a cam associatedtherewith, a pivoted lever mounted within said housmg and adjustable bysaid cam to vary the loading effect of said spring and a screwadjustment associated with said lever and accessible from the exteriorof said housing for varying the loading efiect of said springindependently of said cam.

5. In a circuit controlling device, in combination, a housing open atopposite ends, a control switch including an insulating contact carryingbase mounted within the opening in one end of said housing, a pressureresponsive device mounted upon one of the walls of said housing and having a loading spring associated therewith located within said housing, asnap operating mechanism for said switch mounted within said'housing andoperable by said pressure responsive device to effect opening andclosure of said switch, a face plate detachably mounted upon said housinon the end opposite said control switch, a manual adjusting membermounted upon said face plate and rotatable in opposite directionsbetween given extreme positions, said snap operating mechanism beingoperable by said adjusting member upon movement thereof into one extremeposition to effect opening of said switch and said adjusting memberhaving a cam associated therewith, a piv oted lever mounted within saidhousing and adjustable by said cam to vary the loading effect of saidspring, and a screw adjustment associated with said, lever andaccessible from the exterior of said housing for varying the loadingeffect of said spring independently of said earn.

6. In a circuit controlling device, in combination, a switch biasedtoward circuit closin position, a pivoted operating lever for saidswitch movable into a given extreme position to effect opening of saidswitch and into an opposite extreme position to permit closure of saidswitch, a pivoted control lever and a spring operating connectionbetween said levers acting upon movement of said control lever out ofand into a given normal extreme position to effect operation of saidoperating lever with a snap action between its switch opening and switchclosing positions, said control lever being constantly urged by saidspring operating connection toward said normal extreme position.

7. In a circuit controlling device, in combination, a switch biasedtoward circuit closing position, a pivoted operating lever for saidswitch movableinto a given extreme position to effect opening of saidswitch and into an opposite extreme position to permit closure of saidswitch, a pivoted control lever, a spring operating connection betweensaid levers acting upon movement of said control lever out of and into agiven nor- ;mal position to effect movement of said operating lever witha snap action between its switch opening and switch closing positions,said control 1ever being constantly urged by said spring operatingconnection toward its normal extreme position, a loading spring tendingto move said control lever out of normal position and a fluid conditionresponsive device for operating said control lever in opposition to saidloading spring.

opening in one end of said housing, a condition responsive devicemounted upon said base plate and having an associated loading springlocated within said housing, a snapoperating mechanism for said switchmounted within said housing and g operable by said condition responsivedevice to eifeet opening and closure of said control switch, a faceplate mounted upon said housing on the end opposite said control switchand a manual control element rotatably mounted upon said face plate foradjusting said loading spring to vary the pressure values at which saidcontrol switch is opened and closed, said manual control element beingdetachably mounted upon said face plate and being held in assembledposition thereon under the action of said loading spring.

9. In a circuit controlling device, in combination, a control switch, apivoted lever movable into a given extreme position to efiect opening.of said switch and into an opposite extreme position to permit closureof said switch, a second pivoted lever, a spring operating connectionbetween said levers acting upon movement of said second pivoted leverout of and into a given normal extreme position to effect operation ofsaid first lever with a snap action between its switch opening andswitch closing positions, said second lever being constantly urged bysaid spring operating connection toward said normal extreme position, atemperature responsive device for controlling said second lever, saidsecond lever being movable out of said normal position independently ofsaid temperature responsive device, and a manual adiusting elementrotatable in opposite directions,

between given extreme positions to adjust maid temperature responsivedevice and also adapted upon movement into one of its extreme positionsto move said second lever out of normal position for opening of saidcontrol switch independently of said temperature responsive device. 10.A control apparatus comprising in combination, a member movable inopposite directions in response to changes in a condition to becontrolled; a snap acting control mechanism including a snap member anda spring'tor imto be controlled; a snap acting control mechanismincluding a snap member and a spring for imparting movement to the snapmember; a lever movable into and out of engagementwith the firstmentioned member, said spring being connected with the lever tocontinually urge the lever into engagement with the first mentionedmember for causing, the lever to follow the movement of the firstmentioned member when the latter moves in either direction, said springcausing snap movement of said snap member in one direction and then theother when the lever is moved in opposite directions; and means operatedmanually for causing disengagement of the lever and the first mentionedmember and for maintaining the lever in its disengaged positionregardless of movements of the first mentioned member.

12. A control apparatus comprising, in combination, an ladjustabledevice movable m opposite directions in response to changes in acondition to b controlled, a snap acting control mechanism including asnap member and a spring for imparting movement to said snap member, alever movable into and out of engagement with said device, said springbeing connected to said lever to continuously urge said lever intoengagement with said device to cause said lever to follow the movementof said device when th latter moves in either direction, said springcausing snap movement of said snap memberin one direction, and then theother when said lever is moved in opposite directions, an adjustingmechanism for said de-' vice including a manual element movable inopposite directions between given extreme positions, and meansassociated with said manual element and acting upon movement thereofinto one of its extreme positions to disengage said lever from saiddevice and to maintain said lever in its disengaged positionregardlessof movements of said device. r, e

parting movement to the snap member; a lever movable into and out ofengagement with the first mentioned member, said spring be'ing connectedwith the lever to continually urge the lever into engagement with the'flrst mentioned member for causing" the lever to follow the movement ofthe first mentioned member when I bination. a member movable in oppositedirections in response to changes in a condition 13., A controlapparatus comprising, in combination, a device movable in oppositedirections in response to temperature variations, and having anadjustable loading spring associated therewith, a control switch, a snapoperating mechanism for said switch including a control member movableonto! and into a given extreme position to effect snap opening and snapclosure, of said control switch, said control member being movable intoand out of engage'ment with said device and being biased toward saidextreme position to continuously urge the same into engagement with saiddevice for movement with said device when the latter moves in eitherdirection, a manual control element movable in opposite directionsbetween given extreme positions to adjust said loading spring forvariation of the temperature values at which said switch is opened andclosed, and

means associated with said control element and acting upon movementthereof into a given position to cause disengagement of said operatingmember from said device and to maintain said operating member in itsdisengaged position regardless of movement of said device.

CLYDE F. ROBBINS.

